Adding upstream version 1.3.1.upstream/1.3.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 477 insertions, 0 deletions

diff --git a/libpamc/pamc_load.c b/libpamc/pamc_load.c
new file mode 100644
index 0000000..5155e0a
--- /dev/null
+++ b/libpamc/pamc_load.c
@@ -0,0 +1,477 @@
+/*
+ * $Id$
+ *
+ * Copyright (c) 1999 Andrew G. Morgan <morgan@ftp.kernel.org>
+ *
+ * pamc_load
+ */
+
+#include "libpamc.h"
+
+static int __pamc_exec_agent(pamc_handle_t pch, pamc_agent_t *agent)
+{
+    char *full_path;
+    int found_agent, length, reset_length, to_agent[2], from_agent[2];
+    int return_code = PAM_BPC_FAIL;
+
+    if (agent->id[agent->id_length] != '\0') {
+	PAM_BP_ASSERT("libpamc: internal error agent_id not terminated");
+    }
+
+    for (length=0; (length < agent->id_length); ++length) {
+	switch (agent->id[length]) {
+	case '/':
+	    D(("ill formed agent id"));
+	    return PAM_BPC_FAIL;
+	}
+    }
+
+    /* enough memory for any path + this agent */
+    reset_length = 3 + pch->max_path + agent->id_length;
+    D(("reset_length = %d (3+%d+%d)",
+       reset_length, pch->max_path, agent->id_length));
+    full_path = malloc(reset_length);
+    if (full_path == NULL) {
+	D(("no memory for agent path"));
+	return PAM_BPC_FAIL;
+    }
+
+    found_agent = 0;
+    for (length=0; pch->agent_paths[length]; ++length) {
+	struct stat buf;
+
+	D(("path: [%s]", pch->agent_paths[length]));
+	D(("agent id: [%s]", agent->id));
+
+	sprintf(full_path, "%s/%s", pch->agent_paths[length], agent->id);
+
+	D(("looking for agent here: [%s]\n", full_path));
+	if (stat(full_path, &buf) == 0) {
+	    D(("file existis"));
+	    found_agent = 1;
+	    break;
+	}
+    }
+
+    if (! found_agent) {
+	D(("no agent was found"));
+	goto free_and_return;
+    }
+
+    if (pipe(to_agent)) {
+	D(("failed to open pipe to agent"));
+	goto free_and_return;
+    }
+
+    if (pipe(from_agent)) {
+	D(("failed to open pipe from agent"));
+	goto close_the_agent;
+    }
+
+    agent->pid = fork();
+    if (agent->pid == -1) {
+
+	D(("failed to fork for agent"));
+	goto close_both_pipes;
+
+    } else if (agent->pid == 0) {
+
+	int i;
+
+	dup2(from_agent[1], STDOUT_FILENO);
+	dup2(to_agent[0], STDIN_FILENO);
+
+	/* we close all of the files that have filedescriptors lower
+	   and equal to twice the highest we have seen, The idea is
+	   that we don't want to leak filedescriptors to agents from a
+	   privileged client application.
+
+	   XXX - this is a heuristic at this point. There is a growing
+	    need for an extra 'set param' libpamc function, that could
+	    be used to supply info like the highest fd to close etc..
+	*/
+
+	if (from_agent[1] > pch->highest_fd_to_close) {
+	    pch->highest_fd_to_close = 2*from_agent[1];
+	}
+
+	for (i=0; i <= pch->highest_fd_to_close; ++i) {
+	    switch (i) {
+	    case STDOUT_FILENO:
+	    case STDERR_FILENO:
+	    case STDIN_FILENO:
+		/* only these three remain open */
+		break;
+	    default:
+		(void) close(i); /* don't care if its not open */
+	    }
+	}
+
+	/* we make no attempt to drop other privileges - this library
+	   has no idea how that would be done in the general case. It
+	   is up to the client application (when calling
+	   pamc_converse) to make sure no privilege will leak into an
+	   (untrusted) agent. */
+
+	/* we propogate no environment - future versions of this
+           library may have the ability to audit all agent
+           transactions. */
+
+	D(("exec'ing agent %s", full_path));
+	execle(full_path, "pam-agent", NULL, NULL);
+
+	D(("exec failed"));
+	_exit(1);
+
+    }
+
+    close(to_agent[0]);
+    close(from_agent[1]);
+
+    agent->writer = to_agent[1];
+    agent->reader = from_agent[0];
+
+    return_code = PAM_BPC_TRUE;
+    goto free_and_return;
+
+close_both_pipes:
+    close(from_agent[0]);
+    close(from_agent[1]);
+
+close_the_agent:
+    close(to_agent[0]);
+    close(to_agent[1]);
+
+free_and_return:
+    memset(full_path, 0, reset_length);
+    free(full_path);
+
+    D(("returning %d", return_code));
+
+    return return_code;
+}
+
+/*
+ * has the named agent been loaded?
+ */
+
+static int __pamc_agent_is_enabled(pamc_handle_t pch, const char *agent_id)
+{
+    pamc_agent_t *agent;
+
+    for (agent = pch->chain; agent; agent = agent->next) {
+	if (!strcmp(agent->id, agent_id)) {
+	    D(("agent already loaded"));
+	    return PAM_BPC_TRUE;
+	}
+    }
+
+    D(("agent is not loaded"));
+    return PAM_BPC_FALSE;
+}
+
+/*
+ * has the named agent been disabled?
+ */
+
+static int __pamc_agent_is_disabled(pamc_handle_t pch, const char *agent_id)
+{
+    pamc_blocked_t *blocked;
+
+    for (blocked=pch->blocked_agents; blocked; blocked = blocked->next) {
+	if (!strcmp(agent_id, blocked->id)) {
+	    D(("agent is disabled"));
+	    return PAM_BPC_TRUE;
+	}
+    }
+
+    D(("agent is not disabled"));
+    return PAM_BPC_FALSE;
+}
+
+/*
+ * disable an agent
+ */
+
+int pamc_disable(pamc_handle_t pch, const char *agent_id)
+{
+    pamc_blocked_t *block;
+
+    if (pch == NULL) {
+	D(("pch is NULL"));
+	return PAM_BPC_FALSE;
+    }
+
+    if (agent_id == NULL) {
+	D(("agent_id is NULL"));
+	return PAM_BPC_FALSE;
+    }
+
+    if (__pamc_agent_is_enabled(pch, agent_id) != PAM_BPC_FALSE) {
+	D(("agent is already loaded"));
+	return PAM_BPC_FALSE;
+    }
+
+    if (__pamc_agent_is_disabled(pch, agent_id) != PAM_BPC_FALSE) {
+	D(("agent is already disabled"));
+	return PAM_BPC_TRUE;
+    }
+
+    block = calloc(1, sizeof(pamc_blocked_t));
+    if (block == NULL) {
+	D(("no memory for new blocking structure"));
+	return PAM_BPC_FALSE;
+    }
+
+    block->id =	malloc(1 + strlen(agent_id));
+    if (block->id == NULL) {
+	D(("no memory for agent id"));
+	free(block);
+	return PAM_BPC_FALSE;
+    }
+
+    strcpy(block->id, agent_id);
+    block->next = pch->blocked_agents;
+    pch->blocked_agents = block;
+
+    return PAM_BPC_TRUE;
+}
+
+/*
+ * force the loading of a particular agent
+ */
+
+int pamc_load(pamc_handle_t pch, const char *agent_id)
+{
+    pamc_agent_t *agent;
+    int length;
+
+    /* santity checking */
+
+    if (pch == NULL) {
+	D(("pch is NULL"));
+	return PAM_BPC_FALSE;
+    }
+
+    if (agent_id == NULL) {
+	D(("agent_id is NULL"));
+	return PAM_BPC_FALSE;
+    }
+
+    if (__pamc_agent_is_disabled(pch, agent_id) != PAM_BPC_FALSE) {
+	D(("sorry agent is disabled"));
+	return PAM_BPC_FALSE;
+    }
+
+    length = strlen(agent_id);
+
+    /* scan list to see if agent is loaded */
+
+    if (__pamc_agent_is_enabled(pch, agent_id) == PAM_BPC_TRUE) {
+	D(("no need to load an already loaded agent (%s)", agent_id));
+	return PAM_BPC_TRUE;
+    }
+
+    /* not in the list, so we need to load it and add it to the head
+       of the chain */
+
+    agent = calloc(1, sizeof(pamc_agent_t));
+    if (agent == NULL) {
+	D(("no memory for new agent"));
+	return PAM_BPC_FALSE;
+    }
+    agent->id = calloc(1, 1+length);
+    if (agent->id == NULL) {
+	D(("no memory for new agent's id"));
+	goto fail_free_agent;
+    }
+    memcpy(agent->id, agent_id, length);
+    agent->id[length] = '\0';
+    agent->id_length = length;
+
+    if (__pamc_exec_agent(pch, agent) != PAM_BPC_TRUE) {
+	D(("unable to exec agent"));
+	goto fail_free_agent_id;
+    }
+
+    agent->next = pch->chain;
+    pch->chain = agent;
+
+    return PAM_BPC_TRUE;
+
+fail_free_agent_id:
+
+    memset(agent->id, 0, agent->id_length);
+    free(agent->id);
+
+    memset(agent, 0, sizeof(*agent));
+
+fail_free_agent:
+
+    free(agent);
+    return PAM_BPC_FALSE;
+}
+
+/*
+ * what's a valid agent name?
+ */
+
+int __pamc_valid_agent_id(int id_length, const char *id)
+{
+    int post, i;
+
+    for (i=post=0 ; i < id_length; ++i) {
+	int ch = id[i++];
+
+	if (isalpha(ch) || isdigit(ch) || (ch == '_')) {
+	    continue;
+	} else if (post && (ch == '.')) {
+	    continue;
+	} else if ((i > 1) && (!post) && (ch == '@')) {
+	    post = 1;
+	} else {
+	    D(("id=%s contains '%c' which is illegal", id, ch));
+	    return 0;
+	}
+    }
+
+    if (!i) {
+	D(("length of id is 0"));
+	return 0;
+    } else {
+	return 1;                       /* id is valid */
+    }
+}
+
+/*
+ * building a tree of available agent names
+ */
+
+static pamc_id_node_t *__pamc_add_node(pamc_id_node_t *root, const char *id,
+				       int *counter)
+{
+    if (root) {
+
+	int cmp;
+
+	if ((cmp = strcmp(id, root->agent_id))) {
+	    if (cmp > 0) {
+		root->right = __pamc_add_node(root->right, id,
+					      &(root->child_count));
+	    } else {
+		root->left = __pamc_add_node(root->left, id,
+					     &(root->child_count));
+	    }
+	}
+
+	return root;
+
+    } else {
+
+	pamc_id_node_t *node = calloc(1, sizeof(pamc_id_node_t));
+
+	if (node) {
+	    node->agent_id = malloc(1+strlen(id));
+	    if (node->agent_id) {
+		strcpy(node->agent_id, id);
+	    } else {
+		free(node);
+		node = NULL;
+	    }
+	}
+
+	(*counter)++;
+	return node;
+    }
+}
+
+/*
+ * drop all of the tree and any remaining ids
+ */
+
+static pamc_id_node_t *__pamc_liberate_nodes(pamc_id_node_t *tree)
+{
+    if (tree) {
+	if (tree->agent_id) {
+	    free(tree->agent_id);
+	    tree->agent_id = NULL;
+	}
+
+	tree->left = __pamc_liberate_nodes(tree->left);
+	tree->right = __pamc_liberate_nodes(tree->right);
+
+	tree->child_count = 0;
+	free(tree);
+    }
+
+    return NULL;
+}
+
+/*
+ * fill a list with the contents of the tree (in ascii order)
+ */
+
+static void __pamc_fill_list_from_tree(pamc_id_node_t *tree, char **agent_list,
+				       int *counter)
+{
+    if (tree) {
+	__pamc_fill_list_from_tree(tree->left, agent_list, counter);
+	agent_list[(*counter)++] = tree->agent_id;
+	tree->agent_id = NULL;
+	__pamc_fill_list_from_tree(tree->right, agent_list, counter);
+    }
+}
+
+/*
+ * get a list of the available agents
+ */
+
+char **pamc_list_agents(pamc_handle_t pch)
+{
+    int i, total_agent_count=0;
+    pamc_id_node_t *tree = NULL;
+    char **agent_list;
+
+    /* loop over agent paths */
+
+    for (i=0; pch->agent_paths[i]; ++i) {
+	DIR *dir;
+
+	dir = opendir(pch->agent_paths[i]);
+	if (dir) {
+	    struct dirent *item;
+
+	    while ((item = readdir(dir))) {
+
+		/* this is a cheat on recognizing agent_ids */
+		if (!__pamc_valid_agent_id(strlen(item->d_name),
+					   item->d_name)) {
+		    continue;
+		}
+
+		tree = __pamc_add_node(tree, item->d_name, &total_agent_count);
+	    }
+
+	    closedir(dir);
+	}
+    }
+
+    /* now, we build a list of ids */
+    D(("total of %d available agents\n", total_agent_count));
+
+    agent_list = calloc(total_agent_count+1, sizeof(char *));
+    if (agent_list) {
+	int counter=0;
+
+	__pamc_fill_list_from_tree(tree, agent_list, &counter);
+	if (counter != total_agent_count) {
+	    PAM_BP_ASSERT("libpamc: internal error transcribing tree");
+	}
+    } else {
+	D(("no memory for agent list"));
+    }
+
+    __pamc_liberate_nodes(tree);
+
+    return agent_list;
+}